前序：
float a = 3.14;
float b = 42.0;
double result = a + b ;
printf("the result is %f \n",result);
导图如下：
if 和 else.png
深入学习：
#include <stdio.h>
int main(int argc, const char * argv[]) {
// insert code here...
//定义一个卡车重量的变量
float truckWeight = 34567.1;
//根据卡车重量判断是否属于轻型货车
if (truckWeight < 40000.0) {
printf("It is a light truck\n");
}else{
printf("It is a heavy truck\n");
}
return 0;
}
布尔变量：
BOOL isNotLegal = ((truckWeight > 0.0) && (truckWeight < 40000.0));
if (isNotLegal) {
printf("truck weight is legal range.\n");
}
三元运算符：
int minutesPerPound;
if (isNotLegal) {
minutesPerPound = 10;
}else{
minutesPerPound = 20;
}
//可以用下面的三元运算符代替
minutesPerPound = isNotLegal?10:20;
printf("the minutesPerPound is %d.\n",minutesPerPound);
练习题：
阅读下面这段代码：
int i = 20;
int j = 25;
int k = (i > j) ? 10 : 5;
if (5 < j - k) {
printf("the first experssion is true.");
}else if (j > i){
printf("the second experssion is true.");
}else{
printf("Neither expression is true.");
}
试写出控制台的输出结果。
第一个答出结果的有红包发送哦。
